An interactive line chart displays cumulative COVID-19 death counts over time for multiple countries, using a logarithmic y-axis. A Voronoi overlay, built with `d3.Delaunay` and `d3.delaunay.voronoi`, captures mouse hover events across the entire chart area, highlighting the nearest data point and its corresponding country line while displaying a tooltip with the country name, date, and death total. The visualization uses React state for active selection, SVG for rendering, and data sourced from the CSSE COVID-19 time series dataset.